Janusz Korczak is the greatest innovative educator, a wonderful writer, and—most importantly—his books have no sense of being tied to a specific moment or era. Korczak’s books will be read by teachers and parents, children and teenagers in every time, because these books are a synthesis of tragedy and light, soul and mind, and together—service. Service to children, service to children’s happiness. "The Diary" by Janusz Korczak was written in the ghetto in spring–summer 1942; the document of terrible times has a special power, and in full it has never before been translated into Russian. This is his first publication in Russia.